The present invention relates to automated voltage detection, and more specifically to processes, machines, and manufactures, directed to the automated detection, identification, and selection of available alternating voltage power supplies.
Alternating current and voltage can be delivered or made available by a power source in single-phase and multi-phase waveforms. Electrical devices, such as motors, are designed to receive and be powered by one of these waveforms such that single-phase motors cannot run on multi-phase power and vice-versa.
As the name suggests, single-phase alternating power delivers a single waveform over a wire where the voltage ranges between positive and negative peaks while passing through a zero crossing. Comparatively, multi-phase waveform power supplies regularly use multiple wires and deliver several alternating waveforms over one or more wires. The waveforms are often offset in time from one another by a fraction of their period.
Existing power sources, such as the public electrical power supply grid, provide power generally using several kinds of multi-phase power including split-phase and three-phase wye power supplies. Split-phase delivers two waveforms while three-phase delivers three waveforms. Both systems may use four wires to transmit the power. In the split-phase system, two voltage waveforms may be sent over two wires 180° out of phase with each other. In the three-phase system, three voltage waveforms may be sent over three wires 120° out of phase with each other. Thus, the same four wires on the power grid can provide power with differing characteristics and properties.
Split-phase four wire power lines may have four connections to an AC power grid: L1, L2, N, and G, where the “lines” L1 and L2 are the main power lines that carry current, where “N” is the grid neutral, and “G” is the safety ground. In normal operation, neither the neutral nor the safety ground carries any current, however, in the event of a fault, the ground can carry current.
In a split-phase, 240-V connection system (typical of U.S. residential power supplies), L1 and L2 have a voltage of about 120 V with respect to N and are 180 degrees out of phase.νL1-N=Vp sin(ωt)νL2-N=Vp sin(ωt−φsplit)Here, the peak line-to-neutral voltage is nominally Vp=√{square root over (2)}(120 V) and the phase shift is φsplit=π rad, or 180 degrees. The frequency is ω.
For the three-phase, 208-V, Y-connected system (or wye-connected system) there are three voltage supplies each sharing a common (neutral, N) connection. The voltages have time-varying values ideally of the form:νA-N=Vp sin(ωt)νB-N=Vp sin(ωt−φY)νC-N−Vp sin(ωt+φY)Here, the peak voltage from line to neutral is ideally the same as the split-phase case. The phase shift is instead 120 degrees, or φY=2π/3. The line-to-line voltages are formed from the difference between any two of the three line-to-neutral voltages. The peak line-to-line voltage is √{square root over (3)}Vp and for the 208-V system, √{square root over (2)}Vp=√{square root over (2)}(208 V).
Embodiments provided herein are directed to, among other things, processes, machines, and manufactures supporting the automated detection, identification, and selection of available alternating voltage power supplies, including power grids supplying single-phase power and multi-phase power. Other embodiments, detecting, identifying, and selecting, other voltages and supplies, may be plausible as well.